david@ms.uky.edu (David Herron -- One of the vertebrae) (11/14/89)
There was 3 or 4 RFC's in the 900's which were on the subject of
"transparent subnetting" ... one of the ideas there I thought had
a lot of promise but I don't think is implemented anywhere. The idea
as I recall is to transmit your ARP as always. The gateways take your
ARP and because it's subnet mask isn't right know it's not on the local
subnet and turn around and send it into the other networks they're
attached to. The gateways on those subnets do the same look-at-subnet-
and-rebroadcast-if-necessary routine.
There was a couple of things in there which I don't recall too well
which kept loops from occuring. Also I'm not 100% certain how the
response got back to the sender but it's probably by way of normal
IP routing. Loop prevention could be done with a Usenet Path: style
marker in the packet which records the subnets each instance of the
packet has traversed, but that would break the protocol a bit.
This is tempting because it places all the complications in the
gateways and out of the hosts -- something that is likely a
desirable end goal.
--
<- David Herron; an MMDF guy <david@ms.uky.edu>
<- ska: David le casse\*' {rutgers,uunet}!ukma!david, david@UKMA.BITNET
<-
<- New official address: attmail!sparsdev!dsh@attunix.att.comjfitzger%talcott@wellflt.UUCP (Jeffrey J. Fitzgerald) (11/15/89)
> There was 3 or 4 RFC's in the 900's which were on the subject of > "transparent subnetting" ... one of the ideas there I thought had > a lot of promise but I don't think is implemented anywhere. The idea We support transparent subnetting (as well as the MTU discovery option - another recently discussed topic) and in particular, we will allow multiple subnets to live on the same segment. Proxy ARP is, of course, an important part of transparent subnetting as is the ability to dynamically update your ARP cache by 'peering into' ARP request packets (of hosts that you have previously resolved). This allows you to cable around the gateways using transparent subnetting - or just to change the mac address of one of the hosts - without booting your gateways - or taking any administrative action whatsoever. Jeff